The invention relates to a brake booster for hydraulic brakes.
Many kinds and models of brake booster are already known. The problematic areas that are always in need of improvement are, particularly, the tightness of the brake valve and the question of freedom of movement. Another goal is that the brake booster have as simple a design as possible.
German Patent No. 28 34 008, for example, shows a brake booster in which a control slide that can be acted upon by brake pressure cooperates with a servo piston. In the position of repose, the disconnection of a supply line for power brake fluid is substantially effected by a ring, which is acted upon by reservoir pressure and thus sealingly surrounds a corresponding radial bore in the control slide. However, this arrangement has the disadvantage that to seal off the inlet area from power brake fluid, additional seals must be disposed around the control slide. Upon actuation of the control slide, these seals produce increased friction, so that a strong initial force must be exerted. Moreover, the entire guidance of the slide must be manufactured such that no clamping or seizing occurs, because the control slide must run in the servo piston with very narrow play, so that the return opening will be sealed off upon braking.